No abstract

The purpose of the study is to accelerate the development of ceramic materials for armour applications by substantially increasing the information obtained from a high-energy projectile impact event. This has been achieved by modifying an existing test configuration to incorporate a block of ballistic gel, attached to the strike face of a ceramic armour system, to capture fragments generated during the ballistic event such that their final positions are maintained. Three different materials, representative of the major classes of ceramics for armour applications, alumina, silicon carbide, and boron carbide, have been tested using this system. Ring-on-ring biaxial disc testing has also been carried out on the same materials. Qualitative analysis of the fracture surfaces using scanning electron microscopy and surface roughness quantification, via stereo imaging, has shown that the fracture surfaces of biaxial fragments and ballistic fragments recovered from the edges of the tile are indistinguishable. Although the alumina and boron carbide fragments generated from areas closer to the point of impact were also similar, the silicon carbide fragments showed an increase in porosity with respect to the fragments from further away and from biaxial testing. This porosity was found to result from the loss of a boron-rich second phase, which was widespread elsewhere in the material, although the relevance of this to ballistic performance needs further investigation. The technique developed in this work will help facilitate such studies.

The last seven years have seen the beginning of a new era in heavy transport. Hitherto road transport had been confined to services where it was not economical to lay down a railway track, where the distances were comparatively short and loads comparatively light, and where the lorry could handle goods in special ways not possible on the railway, e. g., in the removal of merchandise direct from gate to gate of factories without wasting time. Today the situation is quite different. The reduced profits of railway companies are ascribed to the competition of road transport and those companies are extending their sphere of operation, not so much by building new tracks, but by the simpler and less costly expedient of running road vehicles. There can be no doubt that the tire manufacturers have been largely responsible for this revolution. Their production of the giant pneumatic tire was the first step, for without this accessory, modern road transport, and modern types of road vehicles, would be unthinkable. The technical reasons for this provide interesting study to engineers, and should indeed be properly understood by all who are interested in the engineering and operating sides of transport problems, if the fullest advantage of tire equipment is to be obtained.